I say go for something known to have a VERY tough body and ambi controls. Pretty much anything modeled after H&K would be nice, but keep in mind the MP5 slither stocks are two position; not adjustable like an M4.
AKs are nice enough but the hook-then-rotate mag attachment can be jammed by someone new to the sport, a high-cap would make that a non issue. AKs do tend to be rather heavy which from my experience would make it a turn off for smaller ladies.
I would also echo the trigger-master set to 3 round burst to keep down the spraying.